The present invention relates generally to containers and, more particulary, to insulated containers that maintain their contents at reduced temperatures
The demands of the modern workplace often leave an individual with little time at the end of the day for the preparation of a meal. Upon returning home, a working individual often does not want to spend time or effort in the kitchen preparing dinner.
Many potential solutions to these problems have been presented. For example, fast food and carry-out restaurants have proven to be quite popular. The individual can pick up his or her dinner on the way home from work. This solution suffers from the disadvantages, however, of a rather limited menu selection and the food is not palatable to many people. Furthermore, the food often gets cold by the time the person arrives home. Frozen meals or "TV dinners" have been around for a long time but, again, many people find that the taste of such prepackaged meals, often prepared weeks or months earlier, leaves a lot to be desired. In addition, maintaining an ample supply of the frozen meals requires excessive freezer space. A demand exists for an alternative approach to provide good quality meals that can be quickly prepared.
In response to this demand, a number of meal delivery services have been developed. These services offer restaurant-quality meals that are delivered frozen to the customer's home, regardless if the customer is home or not. As such, these services offer a high level of convenience for the customer. The services offer a menu with a wide selection of meal choices (as opposed to carry-out foods like burgers, pizza, etc.).
The frozen meals are left on a customer's doorstep in a container much in the same manner that milkmen of days past delivered milk. The containers include a source of refrigeration and are insulated so as to preserve the food in a frozen state. The customer, upon returning home, takes the frozen food out of the container, heats it in an oven and then enjoys a quickly prepared yet fresh tasting, delicious meal. The empty container is left on the customer's doorstep for replacement with a filled container by the delivery service the next day.
To maintain the delivered food in a frozen state, the containers used by the services must be insulated and provide a source of internal refrigeration. The containers currently used feature foam insulation construction and contain gel packs usually filled with phase change material. Such gel packs utilize packaged refrigerant gel that can be chilled to a temperature well below the freezing point of water. As such, frozen gel packs positioned within the container refrigerate any food that is placed within the container. Due to the inefficiency of the foam insulation construction of existing containers, however, a large number of gel packs must be used to keep the food properly frozen during delivery and holding. These gel packs can add 20 lbs. to the weight of the container. This extra weight makes lifting and carrying the containers a difficult chore for the delivery person.
Furthermore, gel packs in existing containers are frozen by placing the gel packs and/or the entire container in a walk-in freezer. The large number of gel packs take a long time to freeze--about 8 hours. In addition, a large freezer space is required to prepare a sufficient number of containers. The required freezers for such an operation are expensive to purchase and use. Workers preparing the containers must also spend a significant amount of time within the freezers and thus suffer prolonged exposure to temperatures of around -18.degree. F. This results in increased worker discomfort, fatigue and potential illness (such as colds).
A number of prior art containers feature freezing agents disposed within their walls and floors as a substitute for gel packs. Examples of such containers may be found in U.S. Pat. No. 4,688,398 to Baek and U.S. Pat. No. 4,981,234 to Slaughter. These containers also must be prepared, that is, their freezing agents frozen, by placement within a freezer space. As such, preparation of a large number of such containers also requires a large amount of expensive freezer space.
Accordingly, it is an object of the present invention to provide an insulated container that may be quickly and efficiently prepared for delivery without the use of a large freezer.
Another object of the invention is to provide an insulated container with very high insulating efficiency due to the use of a vacuum chamber in conjunction with phase change gel packs.
Still another object of the invention is to provide an insulated container that is lightweight but has an extended hold time for foods.